Everybody went crazy when Car And Driver put the new 2020 Toyota Supra on a dyno and found more power at the wheels than what was claimed by Toyota at the crank. Sadly, the Supra’s sister car, the 2020 BMW Z4, isn’t as surprising.
Bimmerpost forum member Joseph (Joe240) sent Jalopnik the recent dyno results of his 2020 BMW Z4 M40i, which is claimed to produce 382 horsepower and 368 lb-ft of torque. To be fair, that’s already way more than the Supra’s 335 HP and 365 lb-ft.
But where the Toyota actually produced an unexpected amount of power at the wheels, the Z4 isn’t so lucky.
As elaborated on in the forum post, Joe did three pulls on the all-wheel dyno at Emerald Coast Motorsports in Fort Walton Beach, Florida. Two in a row, and then a break to avoid suspected heat sink, and then a third pull. Here’s how it went:
That’s 368.6 HP, 373.5 HP, and 362.5 HP, and 415.7 lb-ft of torque, 399.9 lb-ft, and 425.7 lb-ft. Those average out to about 368 HP and 414 lb-ft of torque, all at the wheels.
This is an interesting result, because unlike the Supra, the Z4's power rating of 382 HP at the crank is probably fairly accurate, accounting for driveline losses. But just like the Supra dyno results, the Z4 is making a significant margin of torque more than it’s supposed to—nearly 45 lb-ft between the average of the results and the claimed figure.
So what this suggests, if anything, is that the Supra is underrated on horsepower, the Z4 is probably accurately rated on horsepower, but both automakers have tuned the engines to put down way more torque than advertised. Anything more than listed is a very welcome surprise.